Why not bank them? By what you posted (points expiring in Sept 2021), I can't really tell if your use year is September or October, but in either case, the banking deadlines for those 2020 use year points would be either April 30 or May 31 of 2021.
The earliest that you can bank 2020 use year points is the start of your 2020 use year, so you don't have to decide for several months.